Cleaning compositions for hard surfaces are known. As used herein, the term “hard surfaces” includes glass surfaces and automotive surfaces. As used herein, the term “automotive surface” includes windshields, fenders, tires, doors, roof, hood, trunk, bumpers, trim, windows, hub caps, transportation body and heat exchangers. Such cleaning compositions have been used in household or automotive applications. As used herein, the term “automotive application” includes trains, motorcycles, cars, airplanes, boats, trucks, buses and recreational sporting vehicles and related equipment (e.g., helmets).
Especially with respect to automotive applications, as well as other applications in which the surface to be cleaned is exposed to the environment, an effective cleaning composition should be capable of removing a wide variety of materials including inorganic and organic soils. Typical inorganic soils include clay, cement, industrial dust, sand, products from acid rain condensation, rock forming minerals residue and the like. Typical organic soils include those derived from rubber, asphalt, oil residue, insect residue, tree sap, bird droppings and the like.
Traditional cleaning compositions, however, typically suffer from a number of deficiencies. For example, such compositions generally contain or suggest the use of a high volatile organic compound (“VOC”) content. See, e.g., U.S. Pat. Nos. 5,585,342; 5,415,811; 4,315,828; and 4,213,873. Recently, Federal and State governments have established standards that set specific VOC content limits for several categories of consumer products. See, e.g., EPA Consumer Products Rule, The California Air Resources Board Mid-Term Measures II and The Ozone Transport Commission's Proposed Rule. For example, the new California VOC content limits for non-aerosol glass cleaners and automotive windshield washer fluids are 4% and 1%, respectively, and are expected to be lower in the future. Such standards are based on a finding that VOC emissions from the use of consumer products can cause or contribute to the formation of ground level ozone (“smog”).
However, it has been suggested that lowering the VOC content of traditional cleaning compositions limits their effectiveness and/or range of applications (e.g., are effective for use in light duty applications and not for removing organic soils from hard surfaces in automotive applications). For example, U.S. Pat. No. 4,725,489 (“the '489 patent”) discloses disposable semi-moist wipes for light cleaning of bathroom surfaces. Such wipes carry an aqueous composition containing a VOC content (weight percent solvent) ranging from about 0.2 to about 25%. Wipes carrying a composition having a VOC content of 2.6% exhibited unsatisfactory results, whereas those having a higher VOC content (i.e., a VOC content between 5-7%) exhibited improved results. Similarly, U.S. Pat. No. 4,753,844 (“the '844 patent”) discloses semi-moist wipes for interim cleaning of kitchen surfaces. Such wipes, comprising a “heavy duty” cleaner, have a VOC content ranging from 5-70%.
Although other traditional cleaning compositions are generically described as having a broad range of VOC content, including possibly having a relatively low VOC content, the only specific compositions disclosed as being useful to clean hard surfaces have much higher and prohibitive VOC content. And, none of these disclosed compositions have been shown to be effective in automotive applications.
For example, U.S. Pat. No. 5,437,807 (“the '807 patent”) discloses generally hard surface cleaners comprising, inter alia, an “effective amount” of a solvent in the cleaner with a solvent limit (VOC content) of no more than 50%. However, the '807 patent specifically teaches cleaners comprising approximately 10% solvent. Similarly, U.S. Pat. Nos. 4,315,828 (“the '828 patent”) and 4,054,534 (“the '534 patent”) relate generally to cleaning compositions which may contain a wide range of solvent. The preferred compositions of, and all those specifically disclosed in, the '828 and '534 patents contain, respectively, about 7-15% by weight solvent and 30-95 parts per volume of alcohol per 70-75 parts per volume of water.
Thus, a problem currently facing manufacturers of cleaning products is the need to comply with the new VOC restrictions while, at the same time, maintaining cleaning effectiveness. This problem is especially significant with respect to cleaning products for automotive applications. In addition to the high VOC problem, traditional cleaners for automotive applications, although they are satisfactory in removing inorganic soils from hard surfaces, are often unsatisfactory in removing organic soils. Further, the cleaners currently used, which have a high VOC content, may cause damage to the paint finish.
Manufacturers have attempted to solve these problems by reformulating their existing cleaning compositions in order to lower the VOC content. For example, some windshield washer fluids have been reformulated to contain only “blue” or “green” water (i.e., water containing a blue or green dye) (CLEARLY VISIBLE® Summer Formula from Chem Lab Products, Penske Premium Bug Remover). Other compositions have been reformulated to contain a very small amount of solvent (Splash from FOX Packaging). Unfortunately, these low VOC reformulations have a number of deficiencies including limited cleaning effectiveness especially for organic soils on hard surfaces.
Manufacturers have also attempted to solve the low VOC problem by developing new products. For example, U.S. Pat. No. 6,010,995 discloses an aqueous cleaning/degreasing composition in the form of a macroemulsion comprising a nonionic surfactant and a hydrophobe having specifically enumerated characteristics. Although such compositions contain no or low amounts of VOCs, their effectiveness is limited to cleaning soils derived from Vaseline brand petroleum jelly, ball point pens and felt tip markers and are not effective for cleaning organic soils from hard surfaces.
Additional efforts to effectively remove organic soils from hard surfaces, especially in automotive applications, have other deficiencies. For example, one method for protecting a surface from soils is to apply a protective coating, such as waxes and rinses, to create a water-repellant surface. However, these agents are only minimally effective in removing organic soils.
U.S. Pat. No. 5,871,590 discloses a touchless car wash system in which a composition comprising an ether amine or alkyl ether diamine, a stabilizer and water is sprayed or wiped onto an automotive surface to remove soil. The composition is then removed from the surface using an aqueous rinse. Similarly, U.S. Pat. No. 5,753,310 discloses a method of protecting a vehicle from organic soils in which the vehicle surface is treated with a lecithin and vegetable oil containing composition. See also, U.S. Pat. No. 5,046,449. The treated surface is then easily cleaned of organic soils by rinsing or washing. However, these methods have a number of limitations including the need to use a second rinsing/washing step and the need to reapply the protective coating for future cleaning.
Another method for removing organic soils from automotive surfaces involves the use of compositions containing enzymes. For example, GB 2,283,982 A discloses a two-step method for cleaning a surface carrying a proteinaceous material, comprising applying to the surface an aqueous enzyme formulation, which does not contain surfactant or solvent, to digest the material, and then wiping the surface. Similarly, DE 198 30 848 A1 discloses a surface treatment method in which a formulation containing active enzymes is applied to the surface and the enzymes adhere to the surface in an active immobilized form. Such methods suffer from several deficiencies. First, where the enzyme cleaning formulation does not contain a surfactant or solvent, the ability of the formulation to wet the surface is limited, and consequently, the cleaning formulation coats the surface only where it is applied. The effectiveness of the enzyme is therefore limited to where the cleaning formulation is applied. This is further limited by the ability of the cleaning formulation to penetrate the insect residue, which can require a significant amount of time because insect residues dry very quickly and create a wax-like barrier on the surface that is difficult to penetrate. In addition, such compositions are effective for a limited period of time—the time during which the cleaning formulation is in contact with the insect residue. Further, where the surface is pre-treated with an enzyme formulation, as in DE 198 30 848 A1, enzyme activity decreases with time, especially under the harsh environmental conditions to which automobiles are constantly exposed, such as solar radiation, rapid heating and cooling, erosion by rain and others.
Thus, there remains a need for an effective hard surface cleaner that meets the new governmental VOC content regulations.